i don't thinik it is those they have red dorsal and petra fins.Buenos Aires tetra is the only one somewhat similar to your description that I know of, sorry. I'm interested to know what they are now.
https://www.facebook.com/okaqua/posts/look-at-this-stunning-tetras-%EF%B8%8F/1391415105680738/
Not sure which photo but the one i posted from facebook was actually a video from the amazon and i don't see any indication of doctoring. Perhaps you meant the photo @MattW posted ?I've noticed a new trend with some uncommon species I know very well. It looks like AI is being used to radically accentuate colours that are there, but not like in the commercial photos. In the past, you could look for saturation effects to see doctored colours, but that's becoming impossible now. I think we're going to see a lot of fish reinvented on sales sites.
I couldn't access the photo in question, so this is just a general heads up.